Predefined Constants

IntlCalendar::FIELD_ERA

Calendar field numerically representing an era, for instance
1 for AD and 0 for BC in the
Gregorian/Julian calendars and 235 for the Heisei
(平成) era in the Japanese calendar. Not all calendars have more than
one era.

IntlCalendar::FIELD_YEAR

Calendar field for the year. This is not unique across eras. If the
calendar type has more than one era, generally the minimum value for
this field will be 1.

IntlCalendar::FIELD_MONTH

Calendar field for the month. The month sequence is zero-based, so
Janurary (here used to signify the first month of the calendar; this
may be called another name, such as Muharram in the Islamic calendar)
is represented by 0, February by
1, …, December by 11 and, for
calendars that have it, the 13th or leap month by
12.

Calendar field for the day of the month. The same as
IntlCalendar::FIELD_DAY_OF_MONTH, which has a
clearer name.

IntlCalendar::FIELD_DAY_OF_YEAR

Calendar field for the day of the year. For the Gregorian calendar,
starts with 1 and ends with
365 or 366.

IntlCalendar::FIELD_DAY_OF_WEEK

Calendar field for the day of the week. Its values start with
1 (Sunday, see IntlCalendar::DOW_SUNDAY
and subsequent constants) and the last valid value is 7 (Saturday).

IntlCalendar::FIELD_DAY_OF_WEEK_IN_MONTH

Given a day of the week (Sunday, Monday, …), this calendar
field assigns an ordinal to such a day of the week in a specific month.
Thus, if the value of this field is 1 and the value of the day of the
week is 2 (Monday), then the set day of the month is the 1st Monday of the
month; the maximum value is 5.

Additionally, the value 0 and negative values are
also allowed. The value 0 encompasses the seven days
that occur immediately before the first seven days of a month (which
therefore have a ‘day of week in month’ with value
1). Negative values starts counting from the end of
the month – -1 points to the last occurrence of a
day of the week in a month, -2 to the second last,
and so on.

Calendar field for the localized day of the week. This is a value
betwen 1 and 7,
1 being used for the day of the week that matches
the value returned by
IntlCalendar::getFirstDayOfWeek().

IntlCalendar::FIELD_EXTENDED_YEAR

Calendar field for a year number representation that is continuous
across eras. For the Gregorian calendar, the value of this field
matches that of IntlCalendar::FIELD_YEAR for AD
years; a BC year y is represented by -y +
1.

IntlCalendar::FIELD_JULIAN_DAY

Calendar field for a modified Julian day number. It is different from a
conventional Julian day number in that its transitions occur at local
zone midnight rather than at noon UTC. It uniquely identifies a date.

IntlCalendar::FIELD_MILLISECONDS_IN_DAY

Calendar field encompassing the information in
IntlCalendar::FIELD_HOUR_OF_DAY,
IntlCalendar::FIELD_MINUTE,
IntlCalendar::FIELD_SECOND and
IntlCalendar::FIELD_MILLISECOND. Range is from the
0 to 24 * 3600 * 1000 - 1. It is
not the amount of milliseconds ellapsed in the day since on DST
transitions it will have discontinuities analog to those of the wall
time.

IntlCalendar::FIELD_IS_LEAP_MONTH

Calendar field whose value is 1 for indicating a
leap month and 0 otherwise.